Hi Christian,

OK, I understand now.

The issue occurred in a JSON API that outputs simple maps without sequence values. I lost sight of the distinction between maps and JSON objects, and mistakenly assumed the problem was with the function rather than with serialization.

Simply looking up the actual error code (or paying attention to its SERE prefix) should have kept me from asking in the first place. Sorry for the noise.

But thank you for the quick reply.

Best,
Tom

Hi Tom,

The error is caused by your intent to serialize the map as JSON. You should get a successful response if you replace 'json' with 'basex' or 'adaptive'.

If you want to output data as JSON, it is handy indeed if value lists are represented as arrays. However, most features of XQuery treat sequences as first-class citizens, and JSON serialization is just one use case.

Hope this helps, 

Christian

____________________________________

Dr. Christian Grün, BaseX GmbH, basexgmbh.de
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---

From: Tom De Herdt via BaseX-Talk <basex-talk@mailman.uni-konstanz.de>
Sent: Saturday, November 15, 2025 5:50:27 PM
To: BaseX <basex-talk@mailman.uni-konstanz.de>
Subject: [basex-talk] Issue with request:parameter-map and repeated query parameters

 

Hello,

I’ve encountered an issue with the new request:parameter-map function in
BaseX. It throws an error when called with a query string that contains
repeated parameters, such as ?a=1&a=2:

[SERE0023] Value has more than one item.

Is this behavior expected? As far as I know, query parameters may be
repeated. For example, this can occur when submitting a form with
checkboxes using the GET method. Additionally, JavaScript provides the
URLSearchParams.getAll(<name>) method, which returns an array of values
for a given parameter <name>.

Wouldn't it be more logical for request:parameter-map to also return an
array in such cases?

I’ve tested this issue with BaseX 12 on Windows, using the following
RESTXQ function:

declare
   %rest:GET
   %rest:path("test")
   %output:method("json")
function page:test() {
   request:parameter-map()
};

Any insights are appreciated.

Regards,
Tom De Herdt